The present invention relates to innovative, quick-curing adhesives based on hydrophilic polyisocyanate prepolymers and intended for use in emergency care for staunching severe bleeding (haemorrhage) and sealing leaks.
A variety of materials used as tissue adhesives are available commercially. They include the cyanoacrylates Dermabond® (octyl 2-cyanoacrylate) and Histoacryl Blue® (butyl cyanoacrylate). A requirement for efficient bonding of the cyanoacrylates are dry substrates. In cases of severe bleeding the adhesive fails.
As an alternative to the cyanoacrylates there are biological adhesives available such as, for example, BioGlue®, a mixture of glutaraldehyde and bovine serum albumen, a variety of collagen- and gelatine-based systems (FloSeal®) and also the fibrin adhesives (Tissucol). These systems serve primarily for haemostasis (stopping bleeding). Apart from the high costs, fibrin adhesives are notable for a relatively weak adhesion and a rapid breakdown, and so can be used only in cases of relatively minor injury on unstretched tissue. Collagen- and gelatine-based systems such as FloSeal® serve exclusively for haemostasis. Moreover, because fibrin and thrombin are obtained from human material, and collagen and gelatine from animal material, there is always a risk of infection in biological systems. Furthermore, biological materials must be given refrigerated storage, and so their use in emergency care such as in disaster zones, for example, or in the case of military deployment, etc., is not possible. In these cases there are QuikClot® or QuikClot ACS+™ available to treat traumatic wounds, QuikClot being a granular mineral which in an emergency is inserted into the wound, where it leads to coagulation as a result of removal of water. In the case of QuikClot® this is a highly exothermic reaction, leading to burns. QuikClot ACS+™ is a gauze into which the salt has been embedded. For haemostasis the system must be pressed firmly onto the wound.
The possible application of polyurethane prepolymers as a haemostatic is addressed in the articles “Isocyanate-terminated urethane prepolymer as bioadhesive material: evaluation of bioadhesion and biocompatibility, in vitro and in vivo assays” (Journal of Biomaterials Science, Polymer Edition (2001), 12(7), 707-719) and “Development of a biodegradable bioadhesive containing urethane groups” (Journal of Materials Science: Materials in Medicine (2008), 19(1), 111-120).
It has now been found that formulations comprising specific hydrophilic polyurethane prepolymers and amino-functional curing agents can be used with outstanding effect as a haemostatic for stopping blood. In addition, the formulations have an advantageous adhesive quality, and so, as well as stopping blood, the effect is achieved at the same time of the fixing of the film formed by the formulation on the injury site. Furthermore, by this means, particularly in the case of relatively severe injury, sections of tissue can be joined to one another again and fixed, which is advantageous for the would healing process.